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Biomedical subjects

C J Phillips

Publications and source records attributed to C J Phillips.

At least 37 records · Page 2Linked to original sources
PubMed2001

The perception of color by cattle and its influence on behavior.

Experiments have suggested that cattle can only discriminate long wavelengths of light (colored red) from short (blue) or medium (green) wavelengths, and not short from medium wavelengths; however, stimuli were inadequately balanced for intensity. In this study, an initial group of calves was trained to discriminate light sources by intensity, and the intensities of short, medium, and long wavelength lights were then varied to determine when the calves perceived them to be isoluminant. A new group of calves was tested for their ability to discriminate between the three isoluminant sources and were able to discriminate between long and short or medium wavelengths (mean correct choice 82 and 89%, respectively) but had limited ability to discriminate between the short and medium wavelengths (three out of seven calves could just discriminate in the first eight tests, but thereafter they all selected at random). The response to three stimuli--novel, fearful, and their handler--was video-recorded in isoluminant short, medium, and long wavelengths and movement was assessed by image analysis. In the fear test (a loud noise behind them), the calves negotiated a barrier and concealed themselves more rapidly in the medium (58 s) than the short wavelength (95 s) light. They performed fewest movements in the medium wavelength light compared with the short and long wavelength lights in the novel stimulus and fear tests. They had stronger movement in the long than the short or medium wavelength light in the novel arena test and in response to the handler, and they took least time to reach the handler in the long wavelength.

Animals↗
PubMed2001

The effects of frequency of feeding a total mixed ration on the production and behavior of dairy cows.

Two experiments were conducted to examine the response of Friesian dairy cows to different frequencies of feeding a total mixed ration. The first compared alternate day with daily feeding. Cows fed on alternate days spent longer feeding, had increased dry matter intakes, and produced more milk, but with reduced protein content, compared with cows fed daily. Those fed daily increased feeding greatly after the food was offered to them. Those fed on alternate days had a smaller increase in feeding when food was offered, and their feeding pattern was similar on feeding and nonfeeding days, suggesting that they could not anticipate the time that food would be offered. However, on days when no food was provided they were less aggressive than cows fed daily. Cows fed daily spent less time grooming themselves and more time standing, suggesting that the extra feeding caused disturbance. A second experiment compared frequent feeding (four times per day) with infrequent feeding (once daily), with the cows fed infrequently being either housed with or apart from the cows fed frequently, to determine whether the disturbance of feeding other cows would affect cows housed in the same building but not fed frequently. Both groups of frequently fed cows spent less time feeding in the morning and more in the evening and had less circadian variation in sleeping and lying ruminating, compared with both groups of cows fed infrequently. Cows fed infrequently and housed by themselves produced more milk but with reduced milk protein concentration, compared with the infrequently and frequently fed cows that were housed together. They also spent more time standing in the feeding passage, not ruminating, and more time grooming themselves, indicating less disturbance. Thus cows fed infrequently had reduced milk yield if they were housed with frequently fed cows, and it is concluded that in both experiments frequent feeding disturbed the cows and reduced milk production.

Aggression↗
PubMed2001

The effects on production and behavior of mixing uniparous and multiparous cows.

The production and behavior of a group of eight multiparous and eight uniparous cows after they were mixed were compared with unmixed groups of 16 multiparous and 16 uniparous cows. The cows grazed pasture (mean height 16 cm) in treatment groups in a daily paddock rotation. The milk yield of mixed cows was 3% less in the first week than cows in the unmixed groups, and 1% less in the 6 wk after mixing. The reduction in milk yield was similar for uni- and multiparous cows. Both uni- and multiparous cows in the mixed group grazed for less time and they stood for longer, particularly in the first week postmixing. The multiparous cows in the mixed group increased their pasture biting rate and became more dominant than the uniparous cows, who spent more time grooming other cows and in aggressive interactions compared with the unmixed group of uniparous cows. We concluded that the mixing of multi- and uniparous cows causes disruption to their grazing and social behavior, which results in a reduction in milk yield.

Aggression↗
PubMed2001

Accumulation of 137Cesium and 90Strontium from abiotic and biotic sources in rodents at Chornobyl, Ukraine.

Bank voles (Clethrionomys glareolus) and laboratory strains of house mice (Mus musculus BALB and C57BL) were relocated into enclosures in a highly contaminated area of the Red Forest near the Chornobyl (Ukraine) Reactor 4 to evaluate the uptake rates of 137Cs and 90Sr from abiotic sources. Mice were provided with uncontaminated food supplies, ensuring that uptake of radionuclides was through soil ingestion, inhalation, or water. Mice were sampled before introduction and were reanalyzed every 10 d for 137Cs uptake. Levels of 90Sr were assessed in subsamples from the native populations and in experimental animals at the termination of the study. Uptake rates in house mice were greater than those in voles for both 137Cs and 90Sr. Daily uptake rates in house mice were estimated at 2.72 x 10(12) unstable atoms per gram (whole body) for 137Cs and 4.04 x 10(10) unstable atoms per gram for 90Sr. Comparable rates in voles were 2.26 x 10(11) unstable atoms per gram for 137Cs and 1.94 x 10(10) unstable atoms per gram for 90Sr. By comparing values from voles in the enclosures to those from wild voles caught within 50 m of the enclosures, it was estimated that only 8.5% of 137Cs was incorporated from abiotic sources, leaving 91.5% being incorporated by uptake from biotic materials. The fraction of 90Sr uptake from abiotic sources was at least 66.7% (and was probably much higher). Accumulated whole-body doses during the enclosure periods were estimated as 174 mGy from intramuscular 137Cs and 68 mGy by skeletal 90Sr in house mice over 40 d and 98 mGy from 137Cs and 19 mGy from 90Sr in voles over 30 d. Thus, uptake of radionuclides from abiotic materials in the Red Forest at Chornobyl is an important source of internal contamination.

Animals↗
PubMed2001

Experimental exposure of naive bank voles (Clethrionomys glareolus) to the Chornobyl, Ukraine, environment: a test of radioresistance.

Previous studies have demonstrated no difference in micronucleus (MN) frequencies between wild rodents chronically exposed to the environmental radiation contamination of the Chornobyl (Ukraine) exclusion zone and those inhabiting reference populations. The aim of the present study was to test the hypothesis that a population of bank voles (Clethrionomys glareolus) has developed radioresistance as a result of 14 years of chronic, low-dose radiation exposure. Naive voles were placed in environmental enclosures in the Red Forest region of the exclusion zone for 30 d. Blood samples were obtained at regular intervals, and the MN assay was used to assess chromosomal damage. Additionally, radionuclide uptake was monitored throughout the study, and dose was documented for each individual as well as for their offspring. Total dose for the voles experimentally exposed in this environment averaged 1.09 Gy (36.20 mGy d(-1)) for the 30-d study period. Our results indicate that exposure to radiation levels well above regulatory statutes did not result in an increased MN frequency. Furthermore, our results do not support the hypothesis that voles chronically exposed to these radiation levels have developed a genetic basis for radioresistance that is unique from that present in naive populations. The use of C. glareolus as a sentinel species for environmental studies of radiation contamination and the question of whether the MN assay is an appropriate endpoint for studies of low-dose, chronic radiation exposure are also discussed.

Adaptation, Physiological↗
PubMed2001

Subchronic exposure of BALB/c and C57BL/6 strains of Mus musculus to the radioactive environment of the Chornobyl, Ukraine exclusion zone.

Environmental contamination resulting from the Chornobyl, Ukraine, disaster offers a unique opportunity to examine the in vivo biological effects of chronic, low-dose exposure to radiation. Laboratory studies of acute exposure to ionizing radiation have been used to estimate risk and potential human health effects by the extrapolation of laboratory data to situations of low-dose environmental radiation exposure. Few studies, however, have explored the biological consequences of low-dose exposure via in situ environmental radiation in a sentinel species. In the present study, laboratory strains of Mus musculus (BALB/c and 57BL/6) were placed in environmental enclosures in the Red Forest region of the Chornobyl exclusion zone. Blood samples were obtained every 10 d, and the micronucleus (MN) test was employed to assess the potential for cytogenetic damage from exposure to Chornobyl radiation. Radionuclide uptake was monitored throughout the study, and dose was estimated for each individual as well as for their offspring. Total dose for the mice experimentally exposed to this environment averaged 1,162 mGy for BALB/c (30 d) and 1,629 mGy for C57BL/6 (40 d). A higher MN frequency for both strains was observed at day 10, although this change was only statistically significant in the C57BL/6 mice (chi2/3 = 13.41, p = 0.003). Subsequent samples from C57BL/6 resulted in values at or less than the initial frequencies. In BALB/c mice, an increase in MN was also evident at day 30 (chi2/3 = 10.38, p = 0.006). The experimental design employed here allows for the incorporation of traditional laboratory strains, as well as transgenic strains of Mus, as sentinels of environmental radiation contamination.

Animals↗
PubMed2000

Frictional properties of cattle hooves and their conformation after trimming.

The conformation of the hooves of nine heifers obtained from an abattoir was measured and their coefficient of static friction (mu) was determined for movement in forward, backward and sideways directions. The hooves were trimmed by the Dutch method and their conformation and p were measured again. Trimming increased mu, and decreased the length of the digit and the angle between it and the floor. The value of mu was considerably greater for movement in a forward or backwards direction than sideways. The relationship between the value of mu for sideways movement and hoof conformation was examined by using 52 lower limbs from a variety of cattle breeds. Although mu was greater for Belgian blue than other cattle breeds, there were no relationships between mu and hoof conformation, including a measure of the roughness of the sole.

Animal Husbandry↗
PubMed2000

Effects of sodium fertilizers and supplements on milk production and mammary gland health.

A series of experiments was conducted to investigate the effects of sodium fertilizers and supplements on the milk production and mammary health of dairy cows. In Expt 1, where sodium fertilizer was applied to productive pastures consisting mainly of the natrophile perennial rye-grass, the herbage sodium content and the milk yield of cows was increased and milk somatic cell count (SCC) reduced. In Expt 2, which used pastures containing less productive, natrophobic grasses and broad-leaved plants in Estonia, sodium fertilizer did not increase herbage sodium content and did not affect milk production or composition. In Expt 3 the sodium content of the diet of individually tethered cows was increased from 1 to either 6 or 11 g/kg dry matter (DM) by adding salt to their restricted feed allowance, and the cows' milk yield was increased by the high level of sodium supplement and milk SCC were reduced by both levels of sodium supplement. The calcium and magnesium status of cows was improved by the sodium supplement. In Expt 4 a low level of supplementary salt was included in the ration of tethered cows to increase the sodium content of the diet from 2 to 3.6 g/kg DM. No effects on milk yield or SCC were found, but the sodium supplement reduced Staphylococcus aureus contamination of the milk, but not the proportion of milk samples infected with Escherichia coli. It was concluded that the optimum dietary sodium concentration for maximum milk yield was greater than the published requirements, and that substantial increases in sodium intake above current requirements also reduced milk SCC.

Animal Feed↗
PubMed2000

Organic secretion by striated ducts.

In addition to their role in electrolyte homeostasis, striated ducts in the parotid and submandibular glands of many mammalian species engage in secretion of organic products. This secretion usually is in the form of serous-like granules that lack substructure. Usually, the granules are in the 2.0-2.5 mm range, but granules smaller than 0.1 mm and larger than 12 mm have been observed. In mustelids, striated duct cells contain rhomboidal crystalloids in their apical cytoplasm; in dogs and at least two bat species, the apical plasmalemma is festooned with perpendicularly-oriented rods. Rather than granules, the supranuclear cytoplasm of duct cells in a number of species contains spherical or oblong vesicles. These may convey glycoproteins to the luminal surface where they are incorporated into the glycocalyx or the plasma membrane. Certain vesicles appear to be involved in the uptake of foreign proteins introduced retrogradely into the main excretory duct or of altered proteins produced by acinar cells in streptozotocin-induced diabetes.

Animals↗
PubMed2000

Effects of agronomic treatments on structure and function of ammonia-oxidizing communities.

The aim of this study was to determine the effects of different agricultural treatments and plant communities on the diversity of ammonia oxidizer populations in soil. Denaturing gradient gel electrophoresis (DGGE), coupled with specific oligonucleotide probing, was used to analyze 16S rRNA genes of ammonia oxidizers belonging to the beta subgroup of the division Proteobacteria by use of DNA extracted from cultivated, successional, and native deciduous forest soils. Community profiles of the different soil types were compared with nitrification rates and most-probable-number (MPN) counts. Despite significant variation in measured nitrification rates among communities, there were no differences in the DGGE banding profiles of DNAs extracted from these soils. DGGE profiles of DNA extracted from samples of MPN incubations, cultivated at a range of ammonia concentrations, showed the presence of bands not amplified from directly extracted DNA. Nitrosomonas-like bands were seen in the MPN DNA but were not detected in the DNA extracted directly from soils. These bands were detected in some samples taken from MPN incubations carried out with medium containing 1,000 microg of NH(4)(+)-N ml(-1), to the exclusion of bands detected in the native DNA. Cell concentrations of ammonia oxidizers determined by MPN counts were between 10- and 100-fold lower than those determined by competitive PCR (cPCR). Although no differences were seen in ammonia oxidizer MPN counts from the different soil treatments, cPCR revealed higher numbers in fertilized soils. The use of a combination of traditional and molecular methods to investigate the activities and compositions of ammonia oxidizers in soil demonstrates differences in fine-scale compositions among treatments that may be associated with changes in population size and function.

Agriculture↗
PubMed2000

Economic analysis of long-term reversible contraceptives. Focus on Implanon.

OBJECTIVE: To examine the economic impact of a new implantable contraceptive, Implanon, in comparison with other available contraceptive methods. DESIGN: This was a modelling study using cost data derived from national published sources and effectiveness data from either controlled clinical trials (Implanon) or reports in the literature (other contraceptives). In the baseline analysis, Implanon was compared with 2 long term reversible contraceptives, Norplant and Mirena. Further analyses were then carried out comparing Implanon with Depo-Provera and with combined oral contraceptives. SETTING: The study concentrated on the UK, but also made reference to several other European countries. MAIN OUTCOME MEASURES AND RESULTS: The baseline analysis showed that all 3 long term reversible contraceptives produce very good rates of return, with Implanon providing the best rate of return (both average and internal) of the 3 methods. The payback period for Implanon was calculated as 146 days, compared with 339 and 368 days for Norplant and Mirena, respectively. In terms of cost effectiveness, the cost per protected year for Implanon was 95 Pounds, compared with 146 Pounds and 168 Pounds for Norplant and Mirena, respectively. In comparison with Depo-Provera (an injectable contraceptive), Implanon was both less costly and more effective, the cost per protected year for Depo-Provera being 131 Pounds. The threshold beyond which Implanon delivers cost savings compared with combined oral contraceptives was at a failure rate of 4.9% for the combined pill. CONCLUSIONS: Reversible long term approaches to contraception provide an effective and efficient use of healthcare resources and generate an excellent return on public investment. Implanon produces better rates of return than both Norplant and Mirena, and is also more cost effective in terms of cost per pregnancy avoided and cost per protected year than Norplant, Mirena, Depo-Provera and oral contraceptives.

Adult↗
PubMed2000

The locomotion of dairy cows on concrete floors that are dry, wet, or covered with a slurry of excreta.

Six dairy cows were trained to individually walk down a concrete aisle for a food reward. Their locomotion was then examined in a switchback experiment as the floor surface of the aisle was changed from dry to wetted concrete or concrete covered by shallow (5 cm) or deep (12.5 cm) slurry from cattle excreta. The static and dynamic frictional coefficients were measured by a tribometer, but did not give a clear indication of the risk of slipping. Cow locomotion was measured over the second half of the aisle, and limb angles recorded as the cow passed a video camera. Wetting the floor did not affect the walking or stepping rate, but it reduced the arc made by the joints of the hindlimb during the supporting phase. Slurry caused the cows to keep their legs more vertical at the end of the support phase, probably to aid lifting the limb out of the slurry. It also caused the cows to place their forelimbs down less vertically at the start of the support phase, probably because of the reduced risk of slip in the slurry. When the floor was covered with either the deep or, to a lesser extent, the shallow slurry, the cows' walking and stepping rates were reduced, and on the floor covered with deep slurry their step length was increased. Therefore slurry reduces the cow's walking speed and alters limb angles during the support phase, producing a different walking pattern from cows on dry or wetted concrete.

Animals↗
PubMed2000

Lipid screening in women.

Evidence of the benefits of lowering cholesterol in various populations continues to grow, but questions persist about screening and treatment of lipid disorders in women. In this paper, we review the distinct features of the epidemiology of lipids and coronary heart disease in women and data from recent long-term treatment trials specific to women. Although data from primary prevention trials in women remain sparse, recent trials demonstrating benefits of cholesterol reduction across a broad range of cholesterol levels and cardiac risk in men and women bolster the conclusion that benefits may extend to asymptomatic women who are otherwise at high risk for coronary disease. Periodic lipid screening beginning in middle age will identify most women who are at high enough risk to merit drug therapy or more intensive individual lifestyle interventions. More detailed consideration of age, diabetes, blood pressure, specific lipid levels, or the ratio of total cholesterol to high-density lipoprotein cholesterol, and other risk factors can more accurately estimate individual risk of coronary heart disease and identify high-risk women most likely to benefit from lipid reduction. Advice about healthy diet, weight control, and physical activity can benefit all women, but authorities differ on the benefits of routine lipid screening in low-risk younger women.

Adult↗
PubMed1999

Ultrastructure of the parotid gland in two species of naked-backed bats.

Naked-backed bats of the genus Pteronotus (family Mormoopidae) occur in the Neotropics from Mexico through northern South America. These are relatively small-sized insectivorous species that frequently roost in caves. Eight specimens of naked-backed bats (Pteronotus parnellii) were live-trapped in Suriname and one in Cuba (P. quadridens). Their parotid glands were fixed in an aldehyde mixture designed for field work and postfixed in the laboratory with osmium tetroxide. Tissues were further prepared for electron microscopy by conventional means. The parotid glands of the two species of Pteronotus closely resemble each other except for the substructure of their serous secretory granules. Serous granules in P. parnellii are bizonal, with a moderately dense inner matrix and an outer, denser corona or crescent. The matrix is occupied by laminae, flakes, and filaments in random array. In contrast, serous granules in P. quadridens consist of a uniform matrix that contains dense, usually stacked toroids or tubules either in random array or packed in bundles. A parotid gland from one specimen of P. parnellii contained an endpiece that consisted of cells that contained giant (up to 9 pm in diameter) serous granules. Serous cells in both species contain aggregates of small, uniformly dense, rod-like, membrane-delimited organelles as well as occasional bundles of cytofilaments. The endpieces are separated from intercalated ducts by a ring of granulated cells that contain secretory granules that often have a bull's-eye configuration. Intercalated and striated ducts are typical in appearance, except that many of the cells in the latter contain small, dense secretory granules in their apical cytoplasm. The parotid glands in the two species of naked-baked bats differ slightly in terms of acinar secretory granule ultrastructure, but otherwise are fairly conservative. It is thought that the glands in these particular bats might represent the "basal" condition of the salivary glands of insectivorous bats and thus can serve as a reference point for making comparisons to the highly diversified (in terms of diet) phyllostomid bats.

Animals↗
PubMed1999

The effects of a post partum injection of prostaglandin F2 alpha on return to oestrus and pregnancy rates in dairy cows.

The interval from calving to conception is unnecessarily long in dairy cows. Post partum administration of prostaglandin F2 alpha can reduce the calving to conception interval, but it is not known whether this is due to advanced return to oestrus, increased oestrus intensity and/or increased pregnancy rates. In two experiments, the treatment of dairy cows with prostaglandin F2 alpha 21 days post partum reduced the interval to first oestrus and first service by about 10 days. The intensity of oestrus was not affected. Pregnancy rates to first service were increased from (on average) 60 to 80%, and the number of services/conception was reduced from 2.0 to 1.3.

Animals↗
PubMed1999

Nitrogen cycling and community structure of proteobacterial beta-subgroup ammonia-oxidizing bacteria within polluted marine fish farm sediments.

A multidisciplinary approach was used to study the effects of pollution from a marine fish farm on nitrification rates and on the community structure of ammonia-oxidizing bacteria in the underlying sediment. Organic content, ammonium concentrations, nitrification rates, and ammonia oxidizer most-probable-number counts were determined in samples of sediment collected from beneath a fish cage and on a transect at 20 and 40 m from the cage. The data suggest that nitrogen cycling was significantly disrupted directly beneath the fish cage, with inhibition of nitrification and denitrification. Although visual examination indicated some slight changes in sediment appearance at 20 m, all other measurements were similar to those obtained at 40 m, where the sediment was considered pristine. The community structures of proteobacterial beta-subgroup ammonia-oxidizing bacteria at the sampling sites were compared by PCR amplification of 16S ribosomal DNA (rDNA), using primers which target this group. PCR products were analyzed by denaturing gradient gel electrophoresis (DGGE) and with oligonucleotide hybridization probes specific for different ammonia oxidizers. A DGGE doublet observed in PCR products from the highly polluted fish cage sediment sample was present at a lower intensity in the 20-m sample but was absent from the pristine 40-m sample station. Band migration, hybridization, and sequencing demonstrated that the doublet corresponded to a marine Nitrosomonas group which was originally observed in 16S rDNA clone libraries prepared from the same sediment samples but with different PCR primers. Our data suggest that this novel Nitrosomonas subgroup was selected for within polluted fish farm sediments and that the relative abundance of this group was influenced by the extent of pollution.

Ammonia↗
PubMed1999

Phylogenetic differences between particle-associated and planktonic ammonia-oxidizing bacteria of the beta subdivision of the class Proteobacteria in the Northwestern Mediterranean Sea.

The aim of this study was to determine if there were differences between the types of ammonia-oxidizing bacteria of the beta subdivision of the class Proteobacteria associated with particulate material and planktonic samples obtained from the northwestern Mediterranean Sea. A nested PCR procedure performed with ammonia oxidizer-selective primers was used to amplify 16S rRNA genes from extracted DNA. The results of partial and full-length sequence analyses of 16S rRNA genes suggested that different groups of ammonia-oxidizing bacteria were associated with the two sample types. The particle-associated sequences were predominantly related to Nitrosomonas eutropha, while the sequences obtained from the planktonic samples were related to a novel marine Nitrosospira group (cluster 1) for which there is no cultured representative yet. A number of oligonucleotide probes specific for different groups of ammonia oxidizers were used to estimate the relative abundance of sequence types in samples of clone libraries. The planktonic libraries contained lower proportions of ammonia oxidizer clones (0 to 26%) than the particulate material libraries (9 to 83%). Samples of the planktonic and particle-associated libraries showed that there were depth-related differences in the ammonia oxidizer populations, with the highest number of positive clones in the particle-associated sample occurring at a depth of 700 m. The greatest difference between planktonic and particle-associated populations occurred at a depth of 400 m, where only 4% of the clones in the planktonic library were identified as Nitrosomonas clones, while 96% of these clones were identified as clones that were related to the marine Nitrosospira species. Conversely, all ammonia oxidizer-positive clones obtained from the particle-associated library were members of the Nitrosomonas group. This is the first indication that Nitrosomonas species and Nitrosospira species may occupy at least two distinct environmental niches in marine environments. The occurrence of these groups in different niches may result from differences in physiological properties and, coupled with the different environmental conditions associated with these niches, may lead to significant differences in the nature and rates of nitrogen cycling in these environments.

Ammonia↗